It is known that roller skates known as in-line skates have become very popular in recent years.
Their increasing demand has been so significant that conventional roller skates with two pairs of twin wheels have practically disappeared.
The success of skates with in-line wheels is such that all sports gear manufacturers are currently ready to market their own range of in-line skates.
These in-line skates substantially have a supporting structure which is rigidly coupled to a shoe in an upward region; the shoe is generally of the type with a rigid shell made of plastics with a soft innerboot, and supports are rigidly fixed to the structure in a downward region; generally four but rarely even three or six wheels arranged in front of each other are articulated to the supports.
The wheels, which have the same diameter and thickness, have a diametrical cross-section which is rounded at its ends, so that the rolling band is particularly narrow.
The ground contact area of each wheel is also particularly narrow and depends on factors such as the type of material (generally a polymer), the weight of the user and the degree of wear.
The technique for using these skates is different from that of twin-wheel skates and is more similar to that of ice skates which, as is known, have a rather long rigid metal blade rigidly coupled edgeways below the shoe.
In skates with in-line wheels, the overall longitudinal dimensions of the wheels even exceed the length of the shoe; while this fact, on the one hand, facilitates travel in a straight line and increases their stability, it entails difficulties in handling turns, which are performed by tilting the entire implement and by changing the direction of each step with respect to the preceding one.
The rigid coupling of the rotation axes of the wheels to the supports also causes every roughness of the ground to be transmitted through the implement to the athlete's leg; this of course worsens control of the implement in addition to having a negative effect on the athlete.
WO93/12846 discloses skates with in-line wheels as defined in the preamble of claim 1.